Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$44.94	3.406%	$46.4707	$46.47	$46.45	$46.50
Purchase #2	$28.25	3.722%	$29.3015	$29.30	$29.30	$29.30
Purchase #3	$183.47	5.752%	$194.0232	$194.02	$194.00	$194.00
Purchase #4	$150.70	5.257%	$158.6223	$158.62	$158.60	$158.60
Purchase #5	$63.59	12.176%	$71.3327	$71.33	$71.35	$71.30
Purchase #6	$104.76	6.654%	$111.7307	$111.73	$111.75	$111.70
Purchase #7	$135.33	3.692%	$140.3264	$140.33	$140.35	$140.30
7 purchase totals =	$711.04		$751.8075	$751.80	$751.80	$751.70